Commissural nts contributes to pressor responses to glutamate
injected into the medial nts of awake rats.
Colombari, Eduardo, Jos[acute]e Vanderlei Menani, and William T.
Talman.
Department of Neurology, University of Iowa and Veterans Affairs
Medical Center, Iowa City, IA 52242 & Department of Physiology,
School of Dentistry UNESP, Araraquara, SP, Brazil
APStracts 3:0051R, 1996.
In the present study we investigated whether interruption of the
chemoreceptor reflex by an electrolytic lesion of the commissural
subnucleus of the nucleus tractus solitarii (commNTS) influenced
pressor and bradycardic responses induced by microinjection of L
-glutamate (L-GLU) into the medial NTS (mNTS) of conscious rats. Seven
days after sham lesions 7 rats demonstrated significant pressor
(DMAP=+333 mmHg) and bradycardic (DHR=-748 bpm) responses to
chemoreceptor reflex activation by i.v. injection of KCN. Likewise,
L-GLU (1 nmol in 100 nl) injected into the mNTS in sham rats induced
pressor (+292 mmHg) and bradycardic responses (-908 bpm). However, in
11 rats with lesions in commNTS, pressor and bradycardic
chemoreceptor reflex responses were abolished, and injection of L-GLU
into the mNTS decreased MAP (-146 mmHg) and HR (-5916 bpm) as is
reported in anesthetized control rats. We conclude that pressor
responses induced by L-GLU microinjected into the baroreceptor reflex
region of mNTS in conscious rats depend on the integrity of the
commNTS, which plays an important role in central chemoreceptor
reflex pathways.
Received 28 August 1995; accepted in final form 11 December 1995.
APS Manuscript Number R531-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 14 February 96